Material handling method



March 12, 1957 J. c. MCKENNA 2,785,018

' MATERIAL HANDLNG METHOD Filed Feb. 17, 1951 I! WIIIW'W United StatesPatent -MATERIAL HANDLINGVMETHD James v(.line McKenna, UniversityHeights, Ohio, assigner to Diamond Alkali Company, Cleveland, Ehio, acorporation of Delaware Application February 17, 1951, SerialNo.f21'1,561

2 Claims. (Cl. 302-29) This invention relates to the transportation ofsolid materials in bulk, and more particularly relates to a methd formoving free-tiowng, nely-divided solids, such as soda ash and the like,in continuous conveyors for relatively short distances. The inventionhas particular application to the unloading o'f'hopper :bottom carswhich, as

is known, are employed for the purpose of railroad transportation ofsolid powdered materials in bulk. This is a continuation-in-part of mycopending application Ser. No. 640,336, iiled January Vl0, 1946, nowabandoned.

Various means -have heretofore been proposed for continuous conveyanceof finely-divided solids through distances, such as are encountered inthe unloading of hopper cars and the like. These have included on theone hand provision of purely gravity unloaders, whereby the material tobe unloaded is s-imply dumped from the hopper of thecar, and on theother hand provision of the aerating type of unloader, where acontinuous membrane permeable to the passage of a gaseous iluid isprovided having substantially no inclination whatsoever or perhaps aslight inclination, and wherein suicient air is passed through the.porous membrane to aerate Vor uidize the material being unloaded,whereby the same is carried to its destination.

The gravity means of unloading is feasible in some instances, especiallywhere excavations of considerable depth are available at unloadingsites. However, the expense of excavation is substantial and theinconvenience of a deep excavation at the point .of unloading is oftennot to be borne, whereby this Vmeans of unloading has come to disfavor.The aerating type of unloader also operates with eiiciency on certaininstallations, but has the disadvantage of substantial expense in that aconsiderable com ressed air system must be provided in order to renderthe same practicable in use. Moreover, it presents aproblem ofmaintenance Vof ythe porous conveyor surface, especially since thedanger ofthe nelydivided solid materials clogging vand'impregnating thesame always exists.

it is an object of the present invention to provide a conveyor means forfree-flowing, finely-divided `solid materials in buik which requires butrelatively slight incl-ination to the horizontal, whereby especially incar unload4 ing operations, deep excavations are avoided.

It is a further object of the -invention to provide a transportationmeans for bulk, finely-divided solids which, though inclined at an angleto the horizontal considerably less than that necessary dor completelygravity conveyance, may nevertheless be operated with substantialreliance upon the aid of gravity and with but minimum reliance upon theaid of a gaseous huid under pressure.

In accordance with the objects stated hereinabove, the present inventioncontemplates a method for moving freeflowing, finely-divided solidsWithout substantial dusting, which includes delivering such a solid to aconduit inclined at an angle to the horizontal plane less than the angleof repose of the solid and enclosed from the open atmosphere,introducing a gaseous iiuid beneath such CTI Patented Mar. l2, A1957 2solid at points in said conduit spaced apart at intervals governed bythe setting up of the solid in repose in the conduit, the gas beingintroduced under apressure suicient only to destroy the repose of thesolid in the conduit, whereby -the solid moves continuously downwardlythrough the conduit under the inuence of gravity.

ln accordance with the present disclosure, the term angle of repose -istaken to mean the angle with the horizontal at which the material willstand when piled. It will be appreciated that unless the angle of reposeVis exceeded in some manner, the material will not flow through theconduit. Thepresent invention combines the effect of gravity, whichseeks to move the material through the conduit, and an induced reductionof the angle of repose, which permits gravity to act on the material,whereby it flows through the conduit. It will be particularly noted thatonly that amount of gas, such as air, necessary to destroy the angle ofrepose need Vbe employed in the method of the present invention and thattherefore the dilicult-ies and disadvantages arising from aeration'offinely-divided materials, such as dusting and the like, which problemsare notable even in closed conveyors where some loss of material anddisadvantageous personnel situations are encountered, are avoided. In nosense is the present invention directed to the aerating of the solidsinvolved as has been taught in the prior art, since insuicient air isemployed to provide true aeration or iluidization; on the contrary, onlysufficient air is used to reduce the angle of repose and cause thematerial to slip in the conduit.

It will be appreciated that therparticle size of the solids to lbetransported, or in the case of the hopper car operation, unloaded, willdetermine to some extent the specific flow characteristics and angle ofrepose of the material and thus the necessary inclination of the conduitand the spacing of the inlets for fluid gas pressure, vas well as theminimum volume of gas necessary to destroy the repose of the material inthe conduit. It will further be appreciated vthat the heavier coarsermaterials will, depending upon their angle of repose, require a greaterinclination of the conveyor and quite possibly a greater volume of -airpossibly at less Vspaced distances along the Vconveyor way than liner,more easilysflowing materials.

Examples of operations-which haverbeencarred ouin accordance with thepresent invent-ioninclude the transportation of light soda ash from -ahoppercanto asuitable receptacle, ittbeing lfound that'lightsodaashhasan angle of repose .of vabout -371/2. Under-these circumstances,afconduit disposed at a 26 angle, :havingside walls an'dlbeingr covered-about'eS inchesabove -theconduit level and about;l2 inches `in width,lwillsuitably convey light-soda ash when airnnder 5-7pounds.perssquareinch gauge pressure is applied at intervals along theconveyor of approximately 3-4 feet.

Simple experimentation with similar materials to be conveyed may be hadwhen it is considered that the angle of repose of most dry, free-flowingmaterials is wel] known or subject to simple ascertainment. For example,the following may be cited as known angles of repose of materials ofthis general order:

Degrees Granular soda ash 35i/2. Coarse sand 35. Unhydrated lime 45.

may be conveniently applied to any relatively free-ilowing, pulverulent,solid material which it is desired to convey in a continuous conveyorsystem. Moreover, while air is the mos/t suitable gaseous fluid to beemployed for the purpose of destroying lthe repose of the solid in theinclmed conveyor, any other suitable inert gas may be employed asdesired.

K Illustrative of an apparatus in which the present invention may bepracticed are the accompanying drawings forming a part of thespecication, in which:

Fig. 1 is an elevation of an Vapparatus employing the principles of theinvention as applied to a railroad hopper car, pants of the drawingbeing in section;

Fig. 2 is an enlarged sectional View of a portion of Fig. 1; and Y vFig. 3 is a section taken on the line 3-*3 of Fig. l.

Referring to the drawings, a conventional hopper car 2 isrshown havingoutlet chute 4, to which may be secured =by any suitable means auxiliarychute means 6 having exible connector 8, which may suitably be of canvasor other dust-retaining cloth, and which is secured to conduit 10,forming a complete passage from the interior of car 2 to the conduit 10,through which the material to be unloaded, suitably light soda ash forthe purpose of this specific construction, will fall entirely by gravityand require no assistance.

Conduit l@ is provided at spaced points with air ducts 12, which may, asshown, if desired, be inserted in the conduit 10 in the form of risers,so that a slight actual fall exists at the point of the air outlet,though this feature is of no significance to the present invention. Asshown more particularly in Fig. 3, air ducts 12 are suitably perforatedacross the entire Width of conduit 10, air being applied thereto frommanifold 14, which itself is attached to a source of compressed air (notshown).

Conduit 10 leads to any suitable delivery point, in the present case thepoint being shown diagrammatically as elevator 16, from which thematerial conveyed from the car and away from the railroad facility maysuitably be disposed in any storage point as desired.

The practice of the method of the present invention in the apparatusdescribed will be yseen to be quite simple in view of the description ofthe apparatus above. Thus, in order to unload the car 2, suitableadjustments are made in the outlet chute 4 to open the same and the sodaash, in this case, descends by gravity into the top of the conduit 10,filling the same. Upon destroying the angle of repose of the material byturning on the air pressure as described above, amounting to 5-7 poundsof superatmospheric pressure, through the air ducts 12, the materialwill ow from the point at the uppermost end of the conduit down theconveyor and will set up again at about the point where the second duct12 is shown, except :that of course air is also applied at this point,whereby the setting up of the material is prevented and the materialthus continues Ito flow to the next set-up point, where again Yatmosphere, introducing gas air destroys its repose until the materialeventually arrives in the elevator 16 and may be conveyed byconventional means to the desired storage point. It will be appreciatedthat fthe flow of material is continuous until the compartment of thecar or the complete car served by the mechanism is emptied of the solidto be moved.

Thus, in accordance with the present invention, means are shown forunloading hopper cars and for conveying solid, pulverulent materialsgenerally which rely upon the movement imparted to the materials bygravity and rely also upon a slight fluid gas pressure'at points in theconduit provided where the material sets up into a state of repose,whereby the repose of the material is destroyed and the sliding progressof the material is continued.

While there have been described various embodiments of the invention,rthe methods described are not intended to be understood as limiting thescope of the invention as it is realized that changes therewithin arepossible and -it is further intended that each element recited in any ofth'e following claims is to be understood as referring to all equivalentelements for accomplishing substantially the same results -insubstantially the same or equivalent manner, it being intended to coverthe invention broadly in whatever form its principle may be utilized.

What is claimed is:

l. The method of conveying free-owing, finely-divided solid materialswithout substantial dusting, which com prises the steps of delivering aquantity of such solids into a gas-impermeable conduit inclined at anangle to the horizontal less than the angle of repose of such solids,and applying gas under pressure beneath said solids suicient only todestroy the repose of said solids in said conduit, said'gas beingintroduced beneath said solids at a plurality of spaced points in saidconduit, whereby the solids move continuously downwardly through theconduit under the influence of gravity.

2. The method for moving free-flowing, timely-divided solids withoutsubstantial dusting, which includes the steps of delivering said solidsto a gas-impermeable conduit inclined at an angle to the horizontalplane less than the angle of repose of said solids and enclosed from thebeneath said solids at points in said conduit spaced apart at intervalsgoverned by the setting up of the solids in repose in the conduit, saidgas being introduced under pressure su'icient only to destroy the reposeof said solids in said conduit, whereby `the solids move continuouslydownwardly through the conduit under the influence of gravity.

